Ion implantation is a preferred method of the semiconductor industry to make the scale of the integrated circuits smaller and the computing power of the semiconductor substrate (e.g., silicon chip) greater. Conventional ion implantation devices have fundamental commonalities. The work piece 335 (e.g., silicon chip) is rotated into the system from an external source when it has been processed to the point that it is prepared for implantation. The ion source 302 is at the other end of the production system (feedstock for ionization may be antimony, arsenic, phosphorus for n type junctions or boron, gallium, indium for p type junctions). Generally, positive ions are used, but negative ions may be used as well. During the beam assembly and ion implantation process, usually, most or all of the system is evacuated so that ions, in the ion beam, do not collide with residual gases. System wide power 301, 340, 339 is supplied where needed and a control system 338 and/or operator oversees the entire process. An ion source feedstock is selected based on p or n type junctions. That ion source is ionized by various methods and extracted through an opening in the ionization chamber 303 by an electrode 305, 336 biased to energize the emitted ion beam 309, generally, at a relatively high energy to mitigate against the propensity for space charge blow-up of like charged ions. The emitted ions form a relatively dense (high current) beam 309 that enters into a beam guide 317 that has a mass analyzer 310, consisting of dipole and/or quadrapole magnetic and/or EM fields that bend the ion beam, within a practical envelope, at an angle approximating 90 degrees from the original flight path. Ion species within the ion beam have differing charge to mass ratios. Consistent integrated circuits on the wafer fall within set parameters of charge to mass ratio for ions that are implanted. Incorrect charge to mass ratio species in the emitted ion beam 309 are eliminated after extraction by the mass analyzer 310 and the mass resolution aperture 314. Differing mass will have differing momentum for that ion species that will isolate the trajectories through the mass analyzer 310. The magnetic fields in the system are controlled so that ion species of greater charge to mass ratio than desired will hit one wall of the beam guide 311 and those species having less charge to mass ratio than desired will hit the other side of the beam guide 311, both being eliminated from the continuing ion beam.
Subsequently, in most conventional ion implantation systems, the ion beam reaches the mass resolving aperture 314. The beam current selected by the mass analyzer 310 has mostly the desired ion species, but still contains some species that are close to the desired mass to charge ratio, but not quite. The mass resolving aperture 314 will have an opening that is smaller than the ion beam envelope emerging from the mass analyzer 126 and will resolve (eliminate) the ion species outside the set aperture opening; those ion species strike the sides of the mass resolving aperture 314 and deposit there.
The testable quality of the product wafer (or other implanted surface) will rely on the consistency of the implants. Both prior to the implantation and/or during the actual implantation, the beam will be scanned 322 and profiled 331, generally, downstream from the aperture 314. The control system 338 would be capable of interpreting the beam profile information, sent to the beam diagnosis system 333, to adjust the aperture at the optimum opening to allow the maximum current within best design parameters of charge to mass ratio for the specific implantation. The present invention gives the control system 338 and the controllers a high degree of flexibility to optimize the beam at the point of the mass resolving aperture 314 by incrementally excluding incorrect ions, with the capability of adjustments in real time.
Downstream from the mass resolving aperture 314, there are a number of other processes and optical effects that may be employed to focus, bend, deflect, converge, diverge, scan, parallelize, and/or decontaminate the ion beam. FIG. 1 is used by way of example, as a conventional ion implantation device. The mass resolving aperture is 314, located just past the mass analyzer 310 in the ion beam envelope 309. Other ion implantation systems vary based on proprietary uses. As, stated before, fundamentals such as the mass resolving aperture are common in almost all of such systems.
The demand for electrical energy in the contiguous U.S. was 746,470 MegaWatts in 2005. Most of the energy was produced by coal (49.7%), nuclear energy (19.3%), and natural gas (18.7%). Unfortunately, transmission of energy from the point of generation to the point of retail sale remains highly inefficient. Energy losses of between 5-8% in 2005 translate to nearly twenty billion ($20,000,000,000) dollars in lost revenues. Nearly all the energy produced passes through high voltage power lines which is then delivered to cities, businesses, and residential areas after being stepped down to lower voltages.
All high voltage power lines use insulated copper wiring due to its relatively cheap cost and electrical resistivity of 17.2×10−5 Ωm, which is good for metals. While these cables allow over 700,000 volt electricity transmission, power lines using copper have serious shortcomings and limitations due to mechanical and electrical constraints of hanging wires. For instance, transmission of electricity through copper cables is incredibly inefficient, with a tremendous amount of energy lost in the form of heat created by resistance of electricity passing through the cable. Moreover, the heat generated can cause deformation and failure of the transmission lines, particularly if they are too long. Other problems include costly rights of way which must be obtained to ensure use of the land for towers which, like the cables suspended therefrom, present aesthetic drawbacks.
Underground cables have several advantages over suspended power cables including longer transmission distances, higher electric loads, reduced right of way property costs and no aesthetic disturbance. Buried copper lines also support minimal weight and have better dielectric insulative coatings which reduce dielectric losses of electricity as compared with hanging lines. However, efficiency loss resulting from resistance is still a major problem. Cryogenic cables are a second underground transmission line option, but require liquid nitrogen stations to remain cooled in conjunction with the other costs. Superconductor power transmission lines are an attractive solution because they would exhibit zero loss due to no electrical resistivity; however processing of the single crystal material into wires of any useful length remains impracticable if not impossible.
Clearly there exists a longstanding need for a more efficient means of transmitting energy over long distances. In order to meet the need in the art, a method and apparatus for power transmission through a confined plasma subjected to a magnetic and/or electromagnetic field is provided.
It is known that glass tubes with electrodes at each end and filled with a noble gas can transmit electricity. These gas tubes are similar to neon tubes when an external electric field is applied. Plasma forms inside the tube under an alternating current electric field of high voltage which ionizes the gas or a portion thereof. Electrons become freed from the parent gas molecules and electrical conductivity is increased relative to that of the gas before the applied electric field. These electrons behave similarly to the free electrons in a metal such as copper.
Even a partially ionized gas in which as little as 1% of the particles are ionized can have the characteristics of a plasma (i.e., response to magnetic fields and high electrical conductivity). The term “plasma density” usually refers to the “electron density”, that is, the number of free electrons per unit volume. The degree of ionization of a plasma is the proportion of atoms which have lost (or gained) electrons, and is controlled mostly by the temperature. A plasma is sometimes referred to as being “hot” if it is nearly fully ionized, or “cold” if only a small fraction (for example 1%) of the gas molecules are ionized. “Technological plasmas” are usually cold in this sense. Even in a “cold” plasma the electron temperature is still typically several thousand degrees Celsius.
The electrical conductivity of plasmas is related to its density. More specifically, in a partially ionized plasma, the electrical conductivity is proportional to the electron density and inversely proportional to the neutral gas density. Put another way, any portion of the gas medium that is not ionized, or that exists by virtue of recombination of its charged particles, will continue to act as an insulator, creating resistance to the transmission of electricity therethrough. The subject invention exploits a plasma's responsiveness to magnetic fields (as well as that of the paramagnetic gas medium) to substantially or entirely obviate this resistance during energy transmission in a manner more fully described herein. Accordingly, the transmission efficiency will be substantially independent of distance but rather a function of 1) ionization, 2) vacuum quality, and 3) magnetic field stratification. Ionization would be optimum photo-electric ionization maintained by UV light saturation; vacuum quality would be high to extremely high, with the determining factor being the MFP (mean free path) of the non-ionized molecules present; magnetic field stratification would be the effect of the static magnetic field to regionalize the non-participating molecules and particles within the chamber.